Eumelanin/Pheomelanin ratio of <i>A. cahirinus</i> from “Evolution Canyon” I, Israel.

<p>(A) in the opposite slopes, (B) across stations. Means with the same letter are not significantly different according to Waller-Duncan k-ratio t-test.</p

Contents of eumelanin and pheomelanin in hairs of spiny mice (<i>Acomys cahirinus</i>) from “Evolution Canyon” I, Israel.

<p>(A) in the opposite slopes, (B) across stations. Means with the same letter are not significantly different according to Waller-Duncan k-ratio t-test.</p

Habitat divergence in “Evolution Canyon”.

<p>(A) photo showing part of the “African” slope (AS)/south-facing slope (SFS) of EC, characterized by light terra rossa soil with a stretch of grass cover that generates a yellow-brownish background. (B) Photo of part of the “European” slope (ES)/north-facing slope (NFS), characterized by dark terra rossa soil and shady, humus-laden dark background.</p

“Evolution Canyon” (EC), Nahal Oren, Israel.

<p>(A) aerial view and (B) cross-section showing the opposing slopes. Note the two habitat types; dry, open habitat (with light colored background) on the “African” slope and humid, closed habitat (with dark-colored background) in the “European” slope.</p

Pelage color variation among populations living in different soil types.

<p>Pelage color variation among populations living in different soil types.</p

Adaptation of Pelage Color and Pigment Variations in Israeli Subterranean Blind Mole Rats, <i>Spalax Ehrenbergi</i>

<div><p>Background</p><p>Concealing coloration in rodents is well established. However, only a few studies examined how soil color, pelage color, hair-melanin content, and genetics (i.e., the causal chain) synergize to configure it. This study investigates the causal chain of dorsal coloration in Israeli subterranean blind mole rats, <i>Spalax ehrenbergi</i>.</p><p>Methods</p><p>We examined pelage coloration of 128 adult animals from 11 populations belonging to four species of <i>Spalax ehrenbergi</i> superspecies (<i>Spalax galili, Spalax golani, Spalax carmeli</i>, and <i>Spalax judaei</i>) and the corresponding coloration of soil samples from the collection sites using a digital colorimeter. Additionally, we quantified hair-melanin contents of 67 animals using HPLC and sequenced the <i>MC1R</i> gene in 68 individuals from all four mole rat species.</p><p>Results</p><p>Due to high variability of soil colors, the correlation between soil and pelage color coordinates was weak and significant only between soil hue and pelage lightness. Multiple stepwise forward regression revealed that soil lightness was significantly associated with all pelage color variables. Pelage color lightness among the four species increased with the higher southward aridity in accordance to Gloger's rule (darker in humid habitats and lighter in arid habitats). Darker and lighter pelage colors are associated with darker basalt and terra rossa, and lighter rendzina soils, respectively. Despite soil lightness varying significantly, pelage lightness and eumelanin converged among populations living in similar soil types. Partial sequencing of the <i>MC1R</i> gene identified three allelic variants, two of which were predominant in northern species (<i>S. galili</i> and <i>S. golani</i>), and the third was exclusive to southern species (<i>S. carmeli</i> and <i>S. judaei</i>), which might have caused the differences found in pheomelanin/eumelanin ratio.</p><p>Conclusion/Significance</p><p>Darker dorsal pelage in darker basalt and terra rossa soils in the north and lighter pelage in rendzina and loess soils in the south reflect the combined results of crypsis and thermoregulatory function following Gloger's rule.</p></div

Pelage color variation between sexes (species and populations' pooled data).

<p>Pelage color variation between sexes (species and populations' pooled data).</p

Patterns of variation across species of mole rats in Israel.

<p>A) genetic variation, B) phenotypic variation, and C) environmental variation.</p

Hair-melanin content variation between sexes (species & populations' pooled data).

<p>Hair-melanin content variation between sexes (species & populations' pooled data).</p

Pheomelanin/eumelanin ratio among <i>Spalax</i> populations across latitude.

<p>Pheomelanin/eumelanin ratio among <i>Spalax</i> populations across latitude.</p